Air intake filter assemblies with actuatable filter slats for heating, ventilation, and/or air conditioning (hvac) systems

ABSTRACT

The present disclosure relates generally to air intake filter assemblies, and more particularly to air intake assemblies for an outdoor portion of a heating, ventilation, and/or air conditioning (HVAC) system. In an embodiment, a filter assembly is configured to filter an airflow entering an air intake of a HVAC unit. The filter assembly includes a support structure and a plurality of filter slats, each having a fine filtration material, each disposed within the support structure, and wherein the plurality of filter slats is configured in a louvered relationship and actuated between a closed configuration through which the airflow passes and an open configuration through which the airflow passes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from and the benefit of U.S.Provisional Application Ser. No. 62/803,115, entitled “AIR INTAKE FILTERASSEMBLIES WITH ACTUATABLE FILTER SLATS FOR HEATING, VENTILATION, AND/ORAIR CONDITIONING (HVAC) SYSTEMS,” filed Feb. 8, 2019, which is hereinincorporated by reference in its entirety for all purposes.

BACKGROUND

The present disclosure relates generally to air intake filter assembliesfor a heating, ventilation, and/or air conditioning (HVAC) system.

HVAC systems are used to control environmental properties, such astemperature and humidity, within a conditioned space. HVAC systems caninclude a microchannel heat exchanger, such as a microchannel condenseror evaporator, located in an outdoor portion of the HVAC system. Thesemicrochannel heat exchangers are designed to receive and exchange heatwith an outdoor airflow during operation of the HVAC system. However,over time, debris from the outdoor environment can accumulate onsurfaces of the microchannel heat exchanger. This debris may include,for example, dust and dirt, plant debris, such as leaves, seeds/seedpods, pollen, and grass clippings. As this debris accumulates, it canobstruct air flow through the heat exchanger and interfere with the heatexchange process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an embodiment of a commercial orindustrial HVAC system, in accordance with an aspect of the presentdisclosure;

FIG. 2 is a perspective cutaway view of an embodiment of a packaged unitof an HVAC system, in accordance with an aspect of the presentdisclosure;

FIG. 3 is a perspective cutaway view of an embodiment of a split systemof an HVAC system, in accordance with an aspect of the presentdisclosure;

FIG. 4 is a schematic diagram of an embodiment of a vapor compressionsystem of an HVAC system, in accordance with an aspect of the presentdisclosure;

FIG. 5 is a perspective view of another embodiment of the HVAC unit ofFIG. 2, in accordance with an aspect of the present disclosure;

FIG. 6 is an exploded diagrammatic view of an embodiment of the filterassembly, in accordance with an aspect of the present disclosure;

FIG. 7 is a perspective view of an embodiment of a fine filter for thefilter assembly of FIG. 6, in accordance with an aspect of the presentdisclosure;

FIG. 8 is a top-down cross-sectional view of an embodiment of a finefilter for the filter assembly of FIG. 6, in accordance with an aspectof the present disclosure;

FIG. 9 illustrates a top-down cross-sectional view of another embodimentof a fine filter for the filter assembly, in accordance with an aspectof the present disclosure;

FIG. 10 illustrates a top-down cross-sectional view of anotherembodiment of a fine filter for the filter assembly, in accordance withan aspect of the present disclosure;

FIG. 11 is an exploded view of another embodiment of the filterassembly, in accordance with an aspect of the present disclosure;

FIG. 12 is an exploded view of another embodiment of the filterassembly, in accordance with an aspect of the present disclosure;

FIG. 13 is a side view of another embodiment of the filter assembly, inaccordance with an aspect of the present disclosure;

FIG. 14 a perspective view of another embodiment of the HVAC unit ofFIGS. 2 and 5, wherein the HVAC unit includes an embodiment of thefilter assembly having movable filter sections, in accordance with anaspect of the present disclosure;

FIG. 15 is a schematic diagram of an embodiment of the filter assemblyof FIG. 14 in an open configuration, in accordance with an aspect of thepresent disclosure;

FIG. 16 is a schematic diagram illustrating the embodiment of the filterassembly illustrated in FIG. 15 in a closed configuration, in accordancewith an aspect of the present disclosure;

FIG. 17 is a schematic diagram illustrating another embodiment of thefilter assembly illustrated in FIG. 15 in an open configuration, inaccordance with an aspect of the present disclosure;

FIG. 18 is a schematic diagram illustrating the embodiment of the filterassembly illustrated in FIG. 17 in a closed configuration, in accordancewith an aspect of the present disclosure; and

FIG. 19 is a schematic diagram illustrating another embodiment of thefilter assembly in a closed configuration, in accordance with an aspectof the present disclosure.

DETAILED DESCRIPTION

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” and “the” are intended to mean thatthere are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Additionally, it should be understood that references to “oneembodiment” or “an embodiment” of the present disclosure are notintended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features.

As set forth above, HVAC systems typically include at least onemicrochannel heat exchanger that is designed to exchange heat with anair volume that is separate from a conditioned air volume. As such,these microchannel heat exchangers are generally disposed in an outdoorportion of the HVAC system and are designed to receive a flow of outdoorair across the heat exchanger. As mentioned, debris from the outdoorenvironment can accumulate on surfaces of the microchannel heatexchanger, which can result in reducing air flow through the heatexchanger and the efficiency of the heat exchange process. It ispresently recognized that it would be desirable to filter this debrisfrom the outdoor air flow to block it from collecting on the surfaces ofthe microchannel heat exchanger. However, it is presently recognizedthat adding a filter in the flow path of the condenser creates apressure drop in the flow path. As a result, the fan of the HVAC unitgenerally moves less outdoor air along the flow path when a filter ispresent relative to operation without the filter present. Furthermore,it is presently recognized that this pressure drop continues to increaseover time as the filter accumulates debris that blocks airflow throughthe filter.

Additionally, as mentioned, outdoor debris may include, for example,dust and dirt, plant debris, such as leaves, seeds/seed pods, pollen,and grass clippings. It is presently recognized that the presence of atleast a portion of this debris can be predicted in a temporal manner.For example, certain types of plant debris may occur during a particularseason or time of year and/or time of day based on the behavior ofregional plant flora and/or landscaping activities. By way of particularexample, certain plants may produce pollen and/or seeds/seedpods inparticular times or seasons of the year. Additionally, in certainregions, dust levels may also predictably increase or decrease atparticular times of the year or the day. Furthermore, it is recognizedthat certain debris can be grouped by size. For example, debris (e.g.,dust and pollen) having a size that is less than about 1 mm (±10%) isdesignated herein as fine debris, while certain debris (e.g., seed pods,grass clippings) having a size that is greater than about 1 mm (±10%) isdesignated herein as coarse debris.

With the foregoing in mind, present embodiments are directed toward afilter assembly for an air intake of a HVAC system that is designed toremove debris from an airflow. More specifically, present embodimentsinclude filter assemblies that are designed to be disposed upstream of amicrochannel heat exchanger of an HVAC unit to capture debris andprevent it from depositing onto a surface of the heat exchanger. Incertain embodiments, the disclosed filter assembly includes inner andouter coarse filters with a fine filter removably loaded therebetween.For such embodiments, the replaceable fine filter includes multiplelevels with respect to the airflow, including an upper level and a lowerlevel, wherein the lower level includes features (e.g., valleys,extensions) that extend in the direction of air flow and that accumulatecaptured debris while still enabling suitable airflow through the filterassembly, limiting the pressure drop across the filter assembly. Inother embodiments, the filter assembly includes a set of movable filtersections, such as filter blades or slats in a louvered arrangement,which can be selectively positioned and moved between an openconfiguration and a closed configuration that blocks both coarse andfine debris from traversing the outdoor air intake. Further, byadjusting the positions of the filter sections to provide a minimumamount of filtration that is suitable for a given environment and time,such embodiments minimize the pressure drop associated with the filterassembly. Accordingly, the disclosed filter assemblies improve theefficiency and the operation of the HVAC system.

Turning now to the drawings, FIG. 1 illustrates an embodiment of aheating, ventilation, and/or air conditioning (HVAC) system forenvironmental management that may employ one or more HVAC units. As usedherein, an HVAC system includes any number of components configured toenable regulation of parameters related to climate characteristics, suchas temperature, humidity, air flow, pressure, air quality, and so forth.For example, an “HVAC system” as used herein is defined asconventionally understood and as further described herein. Components orparts of an “HVAC system” may include, but are not limited to, all, someof, or individual parts such as a heat exchanger, a heater, an air flowcontrol device, such as a fan, a sensor configured to detect a climatecharacteristic or operating parameter, a filter, a control deviceconfigured to regulate operation of an HVAC system component, acomponent configured to enable regulation of climate characteristics, ora combination thereof. An “HVAC system” is a system configured toprovide such functions as heating, cooling, ventilation,dehumidification, pressurization, refrigeration, filtration, or anycombination thereof. The embodiments described herein may be utilized ina variety of applications to control climate characteristics, such asresidential, commercial, industrial, transportation, or otherapplications where climate control is desired.

In the illustrated embodiment, a building 10 is air conditioned by asystem that includes an HVAC unit 12. The building 10 may be acommercial structure or a residential structure. As shown, the HVAC unit12 is disposed on the roof of the building 10; however, the HVAC unit 12may be located in other equipment rooms or areas adjacent the building10. The HVAC unit 12 may be a single package unit containing otherequipment, such as a blower, integrated air handler, and/or auxiliaryheating unit. In other embodiments, the HVAC unit 12 may be part of asplit HVAC system, such as the system shown in FIG. 3, which includes anoutdoor HVAC unit 58 and an indoor HVAC unit 56.

The HVAC unit 12 is an air cooled device that implements a refrigerationcycle to provide conditioned air to the building 10. Specifically, theHVAC unit 12 may include one or more heat exchangers across which an airflow is passed to condition the air flow before the air flow is suppliedto the building. In the illustrated embodiment, the HVAC unit 12 is arooftop unit (RTU) that conditions a supply air stream, such asenvironmental air and/or a return air flow from the building 10. Afterthe HVAC unit 12 conditions the air, the air is supplied to the building10 via ductwork 14 extending throughout the building 10 from the HVACunit 12. For example, the ductwork 14 may extend to various individualfloors or other sections of the building 10. In certain embodiments, theHVAC unit 12 may be a heat pump that provides both heating and coolingto the building with one refrigeration circuit configured to operate indifferent modes. In other embodiments, the HVAC unit 12 may include oneor more refrigeration circuits for cooling an air stream and a furnacefor heating the air stream.

A control device 16, one type of which may be a thermostat, may be usedto designate the temperature of the conditioned air. The control device16 also may be used to control the flow of air through the ductwork 14.For example, the control device 16 may be used to regulate operation ofone or more components of the HVAC unit 12 or other components, such asdampers and fans, within the building 10 that may control flow of airthrough and/or from the ductwork 14. In some embodiments, other devicesmay be included in the system, such as pressure and/or temperaturetransducers or switches that sense the temperatures and pressures of thesupply air, return air, and so forth. Moreover, the control device 16may include computer systems that are integrated with or separate fromother building control or monitoring systems, and even systems that areremote from the building 10.

FIG. 2 is a perspective view of an embodiment of the HVAC unit 12. Inthe illustrated embodiment, the HVAC unit 12 is a single package unitthat may include one or more independent refrigeration circuits andcomponents that are tested, charged, wired, piped, and ready forinstallation. The HVAC unit 12 may provide a variety of heating and/orcooling functions, such as cooling only, heating only, cooling withelectric heat, cooling with dehumidification, cooling with gas heat, orcooling with a heat pump. As described above, the HVAC unit 12 maydirectly cool and/or heat an air stream provided to the building 10 tocondition a space in the building 10.

As shown in the illustrated embodiment of FIG. 2, a cabinet 24 enclosesthe HVAC unit 12 and provides structural support and protection to theinternal components from environmental and other contaminants. In someembodiments, the cabinet 24 may be constructed of galvanized steel andinsulated with aluminum foil faced insulation. Rails 26 may be joined tothe bottom perimeter of the cabinet 24 and provide a foundation for theHVAC unit 12. In certain embodiments, the rails 26 may provide accessfor a forklift and/or overhead rigging to facilitate installation and/orremoval of the HVAC unit 12. In some embodiments, the rails 26 may fitinto “curbs” on the roof to enable the HVAC unit 12 to provide air tothe ductwork 14 from the bottom of the HVAC unit 12 while blockingelements such as rain from leaking into the building 10.

The HVAC unit 12 includes heat exchangers 28 and 30 in fluidcommunication with one or more refrigeration circuits. Tubes within theheat exchangers 28 and 30 may circulate refrigerant, such as R-410A,through the heat exchangers 28 and 30. The tubes may be of varioustypes, such as multichannel tubes, conventional copper or aluminumtubing, and so forth. Together, the heat exchangers 28 and 30 mayimplement a thermal cycle in which the refrigerant undergoes phasechanges and/or temperature changes as it flows through the heatexchangers 28 and 30 to produce heated and/or cooled air. For example,the heat exchanger 28 may function as a condenser where heat is releasedfrom the refrigerant to ambient air, and the heat exchanger 30 mayfunction as an evaporator where the refrigerant absorbs heat to cool anair stream. In other embodiments, the HVAC unit 12 may operate in a heatpump mode where the roles of the heat exchangers 28 and 30 may bereversed. That is, the heat exchanger 28 may function as an evaporatorand the heat exchanger 30 may function as a condenser. In furtherembodiments, the HVAC unit 12 may include a furnace for heating the airstream that is supplied to the building 10. While the illustratedembodiment of FIG. 2 shows the HVAC unit 12 having two of the heatexchangers 28 and 30, in other embodiments, the HVAC unit 12 may includeone heat exchanger or more than two heat exchangers.

The heat exchanger 30 is located within a compartment 31 that separatesthe heat exchanger 30 from the heat exchanger 28. Fans 32 draw air fromthe environment through the heat exchanger 28. Air may be heated and/orcooled as the air flows through the heat exchanger 28 before beingreleased back to the environment surrounding the HVAC unit 12. A blowerassembly 34, powered by a motor 36, draws air through the heat exchanger30 to heat or cool the air. The heated or cooled air may be directed tothe building 10 by the ductwork 14, which may be connected to the HVACunit 12. Before flowing through the heat exchanger 30, the conditionedair flows through one or more filters 38 that may remove particulatesand contaminants from the air. In certain embodiments, the filters 38may be disposed on the air intake side of the heat exchanger 30 toprevent contaminants from contacting the heat exchanger 30.

The HVAC unit 12 also may include other equipment for implementing thethermal cycle. Compressors 42 increase the pressure and temperature ofthe refrigerant before the refrigerant enters the heat exchanger 28. Thecompressors 42 may be any suitable type of compressors, such as scrollcompressors, rotary compressors, screw compressors, or reciprocatingcompressors. In some embodiments, the compressors 42 may include a pairof hermetic direct drive compressors arranged in a dual stageconfiguration 44. However, in other embodiments, any number of thecompressors 42 may be provided to achieve various stages of heatingand/or cooling. As may be appreciated, additional equipment and devicesmay be included in the HVAC unit 12, such as a solid-core filter drier,a drain pan, a disconnect switch, an economizer, pressure switches,phase monitors, and humidity sensors, among other things.

The HVAC unit 12 may receive power through a terminal block 46. Forexample, a high voltage power source may be connected to the terminalblock 46 to power the equipment. The operation of the HVAC unit 12 maybe governed or regulated by a control board 48. The control board 48 mayinclude control circuitry connected to a thermostat, sensors, andalarms. One or more of these components may be referred to hereinseparately or collectively as the control device 16. The controlcircuitry may be configured to control operation of the equipment,provide alarms, and monitor safety switches. Wiring 49 may connect thecontrol board 48 and the terminal block 46 to the equipment of the HVACunit 12.

FIG. 3 illustrates a residential heating and cooling system 50, also inaccordance with present techniques. The residential heating and coolingsystem 50 may provide heated and cooled air to a residential structure,as well as provide outside air for ventilation and provide improvedindoor air quality (IAQ) through devices such as ultraviolet lights andair filters. In the illustrated embodiment, the residential heating andcooling system 50 is a split HVAC system. In general, a residence 52conditioned by a split HVAC system may include refrigerant conduits 54that operatively couple the indoor unit 56 to the outdoor unit 58. Theindoor unit 56 may be positioned in a utility room, an attic, abasement, and so forth. The outdoor unit 58 is typically situatedadjacent to a side of residence 52 and is covered by a shroud to protectthe system components and to prevent leaves and other debris orcontaminants from entering the unit. The refrigerant conduits 54transfer refrigerant between the indoor unit 56 and the outdoor unit 58,typically transferring primarily liquid refrigerant in one direction andprimarily vaporized refrigerant in an opposite direction.

When the system shown in FIG. 3 is operating as an air conditioner, aheat exchanger 60 in the outdoor unit 58 serves as a condenser forre-condensing vaporized refrigerant flowing from the indoor unit 56 tothe outdoor unit 58 via one of the refrigerant conduits 54. In theseapplications, a heat exchanger 62 of the indoor unit 56 functions as anevaporator. Specifically, the heat exchanger 62 receives liquidrefrigerant, which may be expanded by an expansion device, andevaporates the refrigerant before returning it to the outdoor unit 58.

The outdoor unit 58 draws environmental air through the heat exchanger60 using a fan 64 and expels the air above the outdoor unit 58. Whenoperating as an air conditioner, the air is heated by the heat exchanger60 within the outdoor unit 58 and exits the unit at a temperature higherthan it entered. The indoor unit 56 includes a blower or fan 66 thatdirects air through or across the indoor heat exchanger 62, where theair is cooled when the system is operating in air conditioning mode.Thereafter, the air is passed through ductwork 68 that directs the airto the residence 52. The overall system operates to maintain a desiredtemperature as set by a system controller. When the temperature sensedinside the residence 52 is higher than the set point on the thermostat,or a set point plus a small amount, the residential heating and coolingsystem 50 may become operative to refrigerate additional air forcirculation through the residence 52. When the temperature reaches theset point, or a set point minus a small amount, the residential heatingand cooling system 50 may stop the refrigeration cycle temporarily.

The residential heating and cooling system 50 may also operate as a heatpump. When operating as a heat pump, the roles of heat exchangers 60 and62 are reversed. That is, the heat exchanger 60 of the outdoor unit 58will serve as an evaporator to evaporate refrigerant and thereby coolair entering the outdoor unit 58 as the air passes over the heatexchanger 60. The indoor heat exchanger 62 will receive a stream of airblown over it and will heat the air by condensing the refrigerant.

In some embodiments, the indoor unit 56 may include a furnace system 70.For example, the indoor unit 56 may include the furnace system 70 whenthe residential heating and cooling system 50 is not configured tooperate as a heat pump. The furnace system 70 may include a burnerassembly and heat exchanger, among other components, inside the indoorunit 56. Fuel is provided to the burner assembly of the furnace system70 where it is mixed with air and combusted to form combustion products.The combustion products may pass through tubes or piping in a heatexchanger, separate from heat exchanger 62, such that air directed bythe blower 66 passes over the tubes or pipes and extracts heat from thecombustion products. The heated air may then be routed from the furnacesystem 70 to the ductwork 68 for heating the residence 52.

FIG. 4 is an embodiment of a vapor compression system 72 that can beused in any of the systems described above. The vapor compression system72 may circulate a refrigerant through a circuit starting with acompressor 74. The circuit may also include a condenser 76, an expansionvalve(s) or device(s) 78, and an evaporator 80. The vapor compressionsystem 72 may further include a control panel 82 that has an analog todigital (A/D) converter 84, a microprocessor 86, a non-volatile memory88, and/or an interface board 90. The control panel 82 and itscomponents may function to regulate operation of the vapor compressionsystem 72 based on feedback from an operator, from sensors of the vaporcompression system 72 that detect operating conditions, and so forth. Asdiscussed below, in certain embodiments, the control panel 82 mayinclude a clock that tracks a current time and date, and thenon-volatile memory 88 may store information, such as predetermined orpredefined threshold values, target values, or information about periodsof time when debris is known or expected to increase in the outdoorenvironment.

In some embodiments, the vapor compression system 72 may use one or moreof a variable speed drive (VSDs) 92, a motor 94, the compressor 74, thecondenser 76, the expansion valve or device 78, and/or the evaporator80. The motor 94 may drive the compressor 74 and may be powered by thevariable speed drive (VSD) 92. The VSD 92 receives alternating current(AC) power having a particular fixed line voltage and fixed linefrequency from an AC power source, and provides power having a variablevoltage and frequency to the motor 94. In other embodiments, the motor94 may be powered directly from an AC or direct current (DC) powersource. The motor 94 may include any type of electric motor that can bepowered by a VSD or directly from an AC or DC power source, such as aswitched reluctance motor, an induction motor, an electronicallycommutated permanent magnet motor, or another suitable motor.

The compressor 74 compresses a refrigerant vapor and delivers the vaporto the condenser 76 through a discharge passage. In some embodiments,the compressor 74 may be a centrifugal compressor. The refrigerant vapordelivered by the compressor 74 to the condenser 76 may transfer heat toa fluid passing across the condenser 76, such as ambient orenvironmental air 96. The refrigerant vapor may condense to arefrigerant liquid in the condenser 76 as a result of thermal heattransfer with the environmental air 96. The liquid refrigerant from thecondenser 76 may flow through the expansion device 78 to the evaporator80.

The liquid refrigerant delivered to the evaporator 80 may absorb heatfrom another air stream, such as a supply air stream 98 provided to thebuilding 10 or the residence 52. For example, the supply air stream 98may include ambient or environmental air, return air from a building, ora combination of the two. The liquid refrigerant in the evaporator 80may undergo a phase change from the liquid refrigerant to a refrigerantvapor. In this manner, the evaporator 80 may reduce the temperature ofthe supply air stream 98 via thermal heat transfer with the refrigerant.Thereafter, the vapor refrigerant exits the evaporator 80 and returns tothe compressor 74 by a suction line to complete the cycle.

In some embodiments, the vapor compression system 72 may further includea reheat coil in addition to the evaporator 80. For example, the reheatcoil may be positioned downstream of the evaporator relative to thesupply air stream 98 and may reheat the supply air stream 98 when thesupply air stream 98 is overcooled to remove humidity from the supplyair stream 98 before the supply air stream 98 is directed to thebuilding 10 or the residence 52.

It should be appreciated that any of the features described herein maybe incorporated with the HVAC unit 12, the residential heating andcooling system 50, or other HVAC systems. Additionally, while thefeatures disclosed herein are described in the context of embodimentsthat directly heat and cool a supply air stream provided to a buildingor other load, embodiments of the present disclosure may be applicableto other HVAC systems as well. For example, the features describedherein may be applied to mechanical cooling systems, free coolingsystems, chiller systems, or other heat pump or refrigerationapplications that include an outdoor air intake.

FIG. 5 is another perspective view of an embodiment of the HVAC unit 12of FIG. 2. In the illustrated embodiment, the HVAC unit 12 is a singlepackage unit, such as a roof-top HVAC unit. In other embodiments, theHVAC unit 12 may be the outdoor HVAC unit 58 of a residential HVACsystem. With this in mind, the HVAC unit 12 illustrated in FIG. 5includes at least one outdoor air intake 100 that is disposed near theheat exchanger 28, as discussed above with respect to FIG. 2. Duringoperation, the fans 32 draw an airflow 102 from the environment throughthe air intake 100 and through the heat exchanger 28 before driving theairflow 102 through air exhausts 104 associated with the fans 32. Incertain embodiments, the HVAC unit 12 may include multiple air intakes100 on different sides or faces of the unit.

For the HVAC unit 12 of FIG. 5, each outdoor air intake 100 of the unitincludes a filter assembly 110 that blocks or prevents certain debrisfrom entering the unit. As discussed in detail below, each filterassembly 110 of the illustrated embodiment includes a coarse outer mesh112, or another suitable coarse filter, that is designed to block coarsedebris from entering the HVAC unit 12 and at least one fine filter 114disposed behind the coarse outer mesh 112 (downstream with respect tothe airflow 102) that is designed to block fine debris from entering theHVAC unit 12. Moreover, as illustrated below, for certain embodiments ofthe filter assembly 110, the fine filter 114 includes features (e.g.,ridges, extensions, protrusions) that extend in the direction of theairflow 102 and that accumulate fine debris in a manner that limits thepressure drop across the filter assembly 110 during operation of theHVAC unit 12.

The embodiment of the HVAC unit 12 illustrated in FIG. 5 includes atleast one pressure sensor 116 that is communicatively coupled to thecontrol panel 82 and that is designed to measure the pressure dropacross the filter assembly 110 during operation of the unit. Forexample, in certain embodiments, the HVAC unit 12 includes a singledifferential pressure sensor 116 capable of measuring a difference inpressure between the outside of the cabinet 24 of the HVAC unit 12(e.g., on the outside of the filter assembly 110) and the inside of thecabinet 24 (e.g., on the inside of the filter assembly 110, near theheat exchanger 28). In other embodiments, the HVAC 12 may includeseparate pressure sensors that are arranged to collect separate pressuremeasurements on either side of the filter assembly 110, and the controlpanel 82 may calculate the pressure drop based on the difference betweenthe two pressure measurements. Additionally, in certain embodiments, theHVAC unit 12 may include any other suitable sensors, includingtemperature sensors, flow sensors, humidity sensors, and so forth, inaccordance with the present disclosure.

Additionally, the embodiment of the HVAC unit 12 illustrated in FIG. 5also includes a number of water spray jets 118 that are disposed aboveeach air intake 100 of the HVAC unit 12. These water spray jets 118 arecoupled to a water source, such as a water supply pipe of the building10 that is conditioned by the HVAC unit 12 or a reservoir that collectscondensation from the evaporator heat exchanger 30 of the HVAC unit 12during operation, and include electronically controlled valves that arecommunicatively coupled to the control panel 82 of the HVAC unit 12. Forthe illustrated embodiment, it may be appreciated that the water sprayjets 118 can serve multiple purposes during operation of the HVAC unit12. As discussed, the water spray jets 118 may be activated to providecooling and/or cleaning benefits to the filter assembly 110. As such,the control panel 82 of the HVAC unit 12 may activate the water sprayjets 118 at different times, such as when the fans 32 are active orinactive, to provide these benefits. In certain embodiments, the controlpanel 82 may activate the water spray jets 118 according to a predefinedschedule, such as once per day, once per week, every morning, or everyevening. In other embodiments, the control panel 82 may selectivelyactivate the water spray jets 118 in response to particular set ofpredefined conditions. For example, the control panel 82 may selectivelyactivate the water spray jets 118 in response to determining that themeasured pressure drop across the filter assembly 110 has increasedabove a predefined pressure threshold value, in response to determiningthat the outdoor air temperature has exceeded a predefined temperaturethreshold value.

For example, as the water spray jets 118 release a spray of water whenthe fans 32 are active, the airflow 102 drives droplets of water intothe filter assembly 110. As such, the filter assembly 100 acts like acooling pad as heat from the airflow is absorbed by these water dropletsand the droplets evaporate from the filter assembly 110 to form watervapor within the airflow 102, cooling the airflow 102 before it reachesthe heat exchanger 28, thereby enabling the airflow 102 to remove agreater amount of heat from the heat exchanger 28. This cooling effectresults in a reduction of discharge temperature, and thus a reduction inthe power consumption of the compressor 42 of the HVAC unit 12 duringoperation. Additionally, it is presently recognized that the water sprayjets 118 can also be designed to provide a downward spray of wateracross the coarse outer mesh 112 and/or the fine filter 114 of thefilter assembly 110 to wash or flush debris from the filter assembly110. For example, in certain embodiments, the control panel 82 mayactivate the water spray jets 118 during a portion of the operation ofthe HVAC unit 12 in which the fans 32 are not active, and may provide asufficient flow of water to dislodge coarse debris from the surface ofthe coarse outer mesh 112 and/or fine debris from the surface of thefine filter 114 before reactivation of the fans 32. It may beappreciated that washing the filter assembly 110 in this manner reducesthe pressure drop across the filter assembly 110 relative to the filterassembly 110 that has accumulated debris. Also, after washing, thefilter assembly 110 will initially be wet, which can provide the coolingeffect described above once the fans 32 are reactivated.

FIG. 6 is an exploded view of an embodiment of the filter assembly 110.For the illustrated embodiment, the filter assembly 110 includes thecoarse outer mesh 112 and a coarse inner mesh 120, which may be made ofmetal or another suitable structural material, such as a polymer. Theouter mesh 112 is disposed on an outer side of the filter assembly 110,upstream of the other components of the filter assembly 110 with respectto the airflow 102, while the coarse inner mesh 120 is disposed on aninner side of the filter assembly, nearest the heat exchanger 28. Assuch, the respective openings 122 and 124 of the inner mesh 120 and theouter mesh 112 have dimensions that are generally have a size of 1 mm ormore, and therefore, are sized to block the passage of coarse debrisfrom traversing the air intake 100. However, it may be appreciated that,in certain embodiments, the openings 122 of the inner mesh 120 may besubstantially (e.g., 2×, 3×, 5×) larger than the openings 124 of theouter mesh 112 since the outer mesh 112 provides initial coarsefiltration. In certain embodiments, the inner mesh 120 may be integratedinto the cabinet 24 of the HVAC unit 12 or mounted over the air intake100. In still further embodiments, the inner and/or outer meshes 120 and112 may be implemented as perforated plates having openings 122 and 124,respectively.

The embodiment of the filter assembly 110 illustrated in FIG. 6 includesa fine filter 114 having a filtration material 126 and a filter frame orsupport 128. The filtration material 126 is generally a fine filtrationmaterial capable of blocking fine debris from traversing the air intake100 of the HVAC unit 12. In certain embodiments, the filtration material126 may be a flexible, fiber-based filtration medium, such as a fiberglass or a woven fabric filtration medium that includes airflow passages129 smaller than 1 mm. As such, in certain embodiments, the filtrationmaterial 126 is both removable and replaceable with respect to thefilter assembly 110. The filter support 128 may be made of metal oranother suitable structural material. Additionally, the illustratedfilter support 128 includes a number of support rods 130 that extendbetween an upper portion 132 and a lower portion 134 of the filtersupport 128 that are designed to support the filtration material 126.For the illustrated embodiment, the filtration material 126 is woventhrough the support rods 130 such that the resulting fine filter 114 hasa three-dimensional shape, including valleys or extensions of variousshapes and sizes, as discussed below. In some embodiments, the filtersupport 128 and the fine filter 114 are integral. For example, a rigidmaterial may be utilized and formed into the desired shape.

FIG. 7 is a perspective view and FIG. 8 is a top-down cross-sectionalview of an embodiment of the fine filter 114 of the filter assembly ofFIG. 6. The illustrated fine filter 114 includes the filtration material126 loaded into the filter support 128. As such, the fine filter 114 hasa three dimensional shape that limits blockage of the airflow 102 as aresult of captured fine debris. For the illustrated embodiment, the finefilter 114 may be described as a multilevel filter having a first orupper level 133 and a second or lower level 135. More specifically, thelower level 135 of the fine filter 114 includes triangular valleys 136that that extend or protrude in the direction of the airflow 102, givingthe fine filter 114 a zig-zag or accordion-like profile, as bestillustrated in FIG. 8. The illustrated triangular valleys 136 may alsobe described as stretching or extending across a substantial portion ofthe lengths 137 of the filter assembly. As fine debris 138 is removedfrom the airflow 102 and accumulates in the fine filter 114, it isgradually driven toward the base 140 of these triangular valleys 136,which leaves a greater portion of the filtration material 126unobstructed by debris, reducing the pressure drop across the filterassembly 110 as a result of the debris.

For the embodiment illustrated in FIGS. 6-8, the filter assembly 110 maybe installed on the air intake 100 and used in different configurations.For example, in a first configuration, the coarse inner mesh 120 isaffixed to the air intake 100 and filters coarse debris from the airflow102, while the coarse outer mesh 112 and the fine filter 114 are notused. Then, during periods of increased debris, the fine filter 114 andthe coarse outer mesh 112 may be removably affixed to the air intake100, over the coarse inner mesh 120, in a second configuration thatfilters both coarse debris and fine debris from the airflow 102. Thefiltration material 126 of the fine filter 114 can be replaced byremoving the coarse outer mesh 112, removing the filtration material 126from the filter support 128, loading new filtration material 126 intothe filter support 128, and replacing the fine filter 114 between thecoarse meshes 112, 120. In a third configuration, the fine filter 114 isdisposed over the coarse inner mesh 120 without the coarse outer mesh112, which obviates removal of the coarse outer mesh 112 duringreplacement of the filtration material 126 of the fine filter 114.

It may be appreciated that fine filter 114 of the disclosed filterassembly 110 is not limited to triangular valleys 136. For example,FIGS. 9 and 10 illustrate top-down cross sectional views of otherdesigns for the fine filter 114 that have different cross-sectionalshapes for different embodiments of the filter assembly 110. Inparticular, the fine filter 114 illustrated in FIG. 9 includes thefiltration material 126 woven through the support rods 130 of a filtersupport 128, such that the lower level 135 of the fine filter 114includes rounded or undulating valleys 136 that extend or protrude inthe direction of the airflow 102. Unlike the fine filter 114 illustratedin FIG. 8, the embodiment of the fine filter 114 illustrated in FIG. 9lacks support rods 130 disposed at the base 140 of the valleys. Rather,the filtration material 126 is draped over multiple support rods 130 toform each undulating valley 136, such that the base 140 of each valleyremains unobstructed by a support rod 130. The lower level 135 of thefine filter illustrated in FIG. 10 instead includes trapezoidal valleys136 that extend or protrude in the direction of the airflow 102. Similarto the fine filter 114 of FIG. 9, for the embodiment of the fine filter114 illustrated in FIG. 10, the filtration material 126 is draped overmultiple support rods 130 to form each trapezoidal valley 136, such thatthe base 140 of each valley remains unobstructed by a support rod 130.

FIG. 11 is an exploded view of another embodiment of the filter assembly110. For the illustrated embodiment, the filter assembly 110 includes acoarse outer mesh 112, a coarse inner mesh 120, and a filtrationmaterial 126, as discussed above. However, the illustrated embodimentlacks the separate filter support 128 illustrated in FIG. 6. Instead,for the embodiment of the filter assembly 110 illustrated in FIG. 11,the outer mesh 112 and the inner mesh 120 include support rods 130 thatare designed to secure the filtration material 126 in place. Like theembodiment of FIG. 6, the filter assembly 110 of FIG. 11 is formed byweaving the filtration material 126 through the support rods 130, suchthat the filtration material 126 forms a multi-level fine filterincluding the triangular valleys 136, as discussed above. In certainembodiments, the support rods 130 may be disposed on only one of theouter mesh 112 or the inner mesh 120. For example, in certainembodiments, the support rods 130 may be disposed only on the outer mesh112 to enable a service technician to easily remove and replace thefiltration material 126 and/or the outer mesh 112, while leaving theinner mesh 120 affixed to the air intake 100 of the HVAC unit 12.

FIG. 12 is an exploded view and FIG. 13 is a side view of anotherembodiment of the filter assembly 110. Like the filter assembliesdiscussed above, the embodiment of the filter assembly 110 illustratedin FIG. 12 includes a set of rounded extensions 136 (e.g., concave orconvex extensions) that protrude in the direction of the airflow 102.While the illustrated rounded extensions are illustrated as beingrelatively large (e.g., tens of centimeters in diameter), in otherembodiments, these extensions may be relatively small (e.g., a fewmillimeters in diameter) dimple-like extensions. For the illustratedembodiment, each of the inner mesh 120, the outer mesh 112, and thefiltration material 126 include the rounded extensions 136. As such, thefine filter 114 may be described as having a first or upper level 133that corresponds to the planar portion of the filter, and having asecond or lower level 135 that includes the rounded extensions 136. Inother embodiments, the inner mesh 120 may not include rounded extensions136, increasing the distance between planar portions of the inner mesh120 and outer mesh 112 in the filter assembly 110. Additionally, incertain embodiments, the filtration material 126 may initially besubstantially flat and lack the rounded extensions, and may acquire therounded extensions upon being loaded between the inner and outer meshes120 and 112. In other embodiments, the extensions 136 may have an ovularcross-section. Additionally, rather than being arranged in rows andcolumns, in other embodiments, the extensions 136 may be staggered toenable a greater number or a tighter packing of the rounded extensions136 on the surface of the fine filter 114. In still other embodiments,the filtration material 126 may have sufficient structural rigidity tomaintain its shape (e.g., including the rounded extensions 136) withoutthe inner mesh 120 and/or outer mesh 112 being present, and thefiltration material 126 effectively filters both coarse and fine debrisfrom entering the HVAC unit 12. For example, in certain embodiments, thefiltration material 126 may be used in combination with only the innermesh 120, in combination with only the outer mesh 112, or without theinner mesh 120 or outer mesh 112.

FIG. 14 is a perspective view of another embodiment of the HVAC unit 12of FIGS. 2 and 5. The illustrated HVAC unit 12 is a single package unit,such as a roof-top HVAC unit, or may be the outdoor HVAC unit 58 of aresidential HVAC system. The HVAC unit 12 illustrated in FIG. 14includes a number of features discussed above with respect to FIGS. 2and 5, including the cabinet 24, heat exchanger 28 (not shown), airintakes 100, fans 32, pressure sensor 116, and water spray jets 118. Forthe HVAC unit 12 of FIG. 14, another embodiment of the filter assembly110 is disposed over each air intake 100 of the unit to block or preventcertain debris from entering the unit. As discussed in detail below,each filter assembly 110 of the illustrated embodiment includes a numberof filter sections 150, also referred to herein as filter blades orfilter slats, at least a portion of which are movable, such that thefilter sections 150 can be adjusted into different configurations toselectively block or filter coarse debris, fine debris, or a combinationthereof, from traversing the air intake 100, and to minimize thepressure drop across the filter assembly 110. As such, the filter slats150 may be described as being in a louvered relationship with respect toone another. For the illustrated embodiment, each filter assembly 110 isin a closed position, in which adjacent filter slats 150 contact oneanother to form a unified or continuous filter surface 152 that isdesigned to block both coarse and fine debris from traversing the airintake 100. It may be noted that, while the filter slats 150 of eachfilter assembly 110 illustrated in FIG. 14 extend vertically across asubstantial portion of the height 154 of the air intake 100, in otherembodiments, the filter slats 150 may instead extend horizontally acrossa substantial portion of the width 156 of the air intake 100. It may beappreciated that the filter assembly 110 illustrated in FIG. 14 offersan advantage in that certain embodiments of the filter assembly 110 aredesigned to selectively adjust to provide different levels of filteringwithout being manually reconfigured by a service technician.

FIG. 15 is a schematic diagram illustrating an embodiment of the filterassembly 110 illustrated in FIG. 14 in an open configuration. Theembodiment of the filter assembly 110 illustrated in FIG. 15 includes anumber of filter sections 150, which are referred to as filter slats 150(e.g., filter slats 150A, 150B, 150C, 150D, 150E, 150F, 150H, 150I, and150J), each operably coupled to a portion of the support structure 160via a respective rod 162. For this embodiment, each of the filter slats150 may be made of a fine filtration material 126 disposed over arectangular filter frame 164, which may be made of metal or suitablestructural material. Additionally, each respective rod 162 is coupled toeach respective frame 164 and extends out of the respective filtrationmaterial 126 and into corresponding openings in an upper portion 166 ofthe support structure 160 and a lower portion 168 of the supportstructure 160. As such, for the illustrated embodiment, the rods 162secure each of the filter slats 150 to the support structure 160 anddefine a respective rotational axis 170 of each of the filter slats 150,as indicated by the arrows 172A and 172B. In certain embodiments, therods 162 may instead each be implemented as two shorter rods that arecoupled to and extend from the frame 164 of each of the filter slats150.

More specifically, for the filter assembly 110 illustrated in FIG. 15, afirst set of the filter slats 150A, 150C, 150E, 150G, and 150I, extenddeeper into the upper portion 166 of the support structure 160 tooperably couple to an upper transfer or transmission rod 174 disposed inthe upper portion 166. The upper transfer rod 174 is coupled to an uppermotor 176, such that operation of the motor 176 in a first directioncauses the first set of filter slats to rotate in a first direction(e.g., as indicated by the arrow 172A), and operation of the motor 176in a second direction causes the first set of filter slats to rotate ina second direction (e.g., as indicated by the arrow 172B) about theirrespective rotational axes 170. Similarly, a second set of the filterslats 150B, 150D, 150F, 150H, and 150J, extend deeper into the lowerportion 168 of the support structure 160 to operably couple to a lowertransfer rod 178 that is disposed in the lower portion 168. The lowertransfer rod 178 is coupled to a lower motor 180, such that operation ofthe motor 180 in a first direction causes the second set of filter slatsto rotate in a first direction (e.g., as indicated by the arrow 172A)about their respective rotational axes 170, and operation of the motor180 in a second direction causes the second set of filter slats torotate in a second direction (e.g., as indicated by the arrow 172B)about their respective rotational axes 170. It may be appreciated thatthe transfer rods 174, 178 are merely provided as examples, and in otherembodiments, other transfer mechanisms or devices (e.g., drive belts,drive chains, spooled strings) may also be used, in accordance with thepresent disclosure. For reduced cost and complexity, in certainembodiments, the filter assembly 110 may lack a second transfer rod andsecond motor, and all of the filter slats 150 may be operably coupled toa single motor by a single transfer device. Additionally, for reducedcost and complexity, in certain embodiments, the first or the second setof filter slats 150 may be affixed in position, while the remainingfilter slats 150 are rotated to switch the filter assembly 110 to yieldthe open and the closed configurations, also resulting in a design thatincludes fewer components.

Accordingly, for the embodiment of the filter assembly illustrated inFIG. 15, each of the filter slats 150 are rotatable about its respectiverotational axis 170, such that the filter assembly 110 is able to movebetween an open and a closed configuration. Examples of the closedconfiguration are illustrated in FIG. 14, discussed above, and in FIG.16, discussed below. The filter assembly 110 illustrated in FIG. 15 isin an open configuration, in which adjacent filter slats are separatedfrom one another by respective gaps 182. As such, it should beappreciated that while the filtration material 126 of the filter slats150 is itself designed to block fine debris from traversing the airintake 100 of the HVAC unit 12, the illustrated embodiment of the filterassembly 110 in the open configuration may allow some fine debris totraverse the air intake 100 of the HVAC unit 12. That is, in theillustrated open configuration, the gaps 182 between adjacent filterslats 150 of the illustrated filter assembly 110 may be suitably sized(e.g., 1 mm or less) to block coarse debris from traversing the airintake 100 via the gaps 182. While fine debris may still traverse theair intake 100 of the HVAC unit 12 in the open configuration, it is alsopresently recognized that the open configuration provides asubstantially lower pressure drop across the filter assembly 110 thanother filter designs that do not include the gaps 182, and this lowerpressure drop reduces energy consumption of the fans 32 and the HVACunit 12. Additionally, in certain embodiments, the filter assembly 110may include gaps 182 in the open configuration that are substantiallylarger than coarse debris (e.g., greater than 1 mm) to further reduce orsubstantially eliminate the pressure drop across the filter assemblyduring operation. In certain of these embodiments, the filter assembly110 may further include one or more coarse mesh layers, like the coarseinner mesh 120 and/or the coarse outer mesh 112 discussed above,disposed behind and/or in front of the filter slats 150 to block coarsedebris from entering the air intake 100 regardless of the configurationof the filter slats 150.

For the embodiment illustrated in FIG. 15, the upper and lower motors176, 180 are communicatively coupled to the control panel 82 of the HVACunit 12, such that the control panel 82 can provide control signals tothe motors to move the filter slats 150 of the filter assembly 110between the open and closed configurations. In certain embodiments, thefilter assembly 110 or another suitable component of the HVAC unit 12may include one or more sensors 184 that are communicatively coupled tothe control panel 82 and designed to measure the positions of the filterslats 150. For example, the illustrated filter assembly 110 includes asensor 184, such as a displacement sensor or an optical sensor,configured to measure a position of the filter slats 150, or a size ofthe gaps 182 between adjacent filter slats 150, to determine whether thefilter assembly 110 has reached the open or closed configuration. By wayof specific example, in an embodiment, when the control panel 82activates the motors 176 and 180 to move the filter slats 150 to theopen configuration, the sensor 184 may provide measurement signals tothe control panel 82, such that the control panel 82 can determine whenthe gaps 182 are suitable sized (e.g., about 1 mm, ±10%) to capturecoarse debris, and thereby determine that the filter assembly 110 is inthe open configuration. In other embodiments, the filter assembly 110and HVAC unit 12 may lack the sensor 184 and the motors 176, 180 may bestepper motors that have been suitably calibrated such that the controlpanel 82 provides control signals to cause the motors to perform apredetermined number of steps in a predetermined direction to move thefilter slats 150 between the open and closed configurations. In otherembodiments, the position of each of the filter slats 150 may bemanually set and manually adjusted by a service technician duringinstallation or maintenance of the HVAC unit 12. That is, in certainembodiments, the motors 176, 180 may be manually activated by a servicetechnician via inputs provided to the control panel 82 or via a userinput mechanism (e.g., buttons/switches operably coupled to the motors)to achieve a desired open or closed configuration. In still otherembodiments, the illustrated filter assembly 110 may lack the motors176, 180, and may instead be manually positioned by the servicetechnician interacting with the upper and lower transfer rods 174 and178, or manually rotating the filter slats 150 into suitable positionsto achieve the open and closed configurations.

FIG. 16 is a schematic diagram illustrating the embodiment of the filterassembly 110 illustrated in FIG. 15 in a closed configuration. Asillustrated, adjacent filter slats 150 of the filter assembly 110contact one another to form the unified filter surface 152. In certainembodiments, adjacent filter slats 150 may slightly overlap with oneanother, or edges of the filter slats 150 may align with and contact oneanother to form a substantially flat unified filter surface 152. Assuch, during operation of the fans 32 of the HVAC unit 12, the airflow102 traverses the filtration material 126 of the filter slats 150, andthe unified filter surface 152 of the filter assembly 110 blocks bothfine and coarse debris from traversing the air intake 100 of the HVACunit 12. However, it is also noted that, since the closed configurationlacks the gaps 182 illustrated in FIG. 15, the pressure drop across thefilter assembly 110 is generally higher when the filter assembly 110 isin the closed configuration relative to the open configuration.

FIG. 17 is a schematic diagram illustrating another embodiment of thefilter assembly 110 illustrated in FIG. 15. The embodiment of the filterassembly 110 illustrated in FIG. 16 includes a number of filter slats150 (e.g., filter slats 150A-J), each operably coupled to the supportstructure 160, as discussed above. However, for this embodiment, whenmoving between the illustrated open configuration and the closedconfiguration, adjacent filter slats 150 rotate in opposite directions.For the illustrated example, when moving from the open to the closedconfiguration, the first set of filter slats 150A, 150C, 150E, 150G, and150I rotate in a first direction indicated by the arrow 186A and thesecond set of filter slats 150B, 150D, 150F, 150H, and 150J rotate in asecond direction indicated by the arrow 186B. When moving from theclosed to the open configuration, the first set of filter slats 150A,150C, 150E, 150G, and 150I rotate in a first direction indicated by thearrow 188A and the second set of filter slats 150B, 150D, 150F, 150H,and 150J rotate in a second direction indicated by the arrow 188B.

FIG. 18 is a schematic diagram illustrating the embodiment of the filterassembly 110 of FIG. 17 in a closed configuration. As illustrated,adjacent filter slats 150 of the filter assembly 110 contact one anotherto form a unified filter surface 152. It may be noted that, while theunified filter surface 150 may not be perfectly continuous and mayinclude minor spaces at the interfaces between the filter slats 150, itmay be described herein as “continuous” because the overlap and/orengagement of adjacent filter slats 150 creates a connected or unifiedsurface with respect to the airflow 102. As such, during operation ofthe fans 32 of the HVAC unit 12, the airflow 102 is traverses thefiltration material 126 of the filter slats 150, and the unified filtersurface 152 of the filter assembly 110 blocks both fine and coarsedebris from traversing the air intake 100 of the HVAC unit 12. It isalso noted that the unified filter surface 152 of the illustratedembodiment includes triangular valleys 136 that extend or protrude inthe direction of the airflow 102, giving the unified filter surface 152a zig-zag or accordion-like profile similar to the embodiment of FIG. 8.As with the embodiments of the filter assembly 110 discussed above withrespect to FIGS. 5-13, the filtration material 126 in the triangularvalleys 136 of the filter assembly 110 illustrated in FIG. 18 accumulatecoarse and fine debris while other portions of the filtration material126 remain unobstructed, reducing the pressure drop across the filterassembly 110.

FIG. 19 is a schematic diagram illustrating another embodiment of thefilter assembly 110 illustrated in FIGS. 17 and 18 in a closedconfiguration. Like the embodiments of the filter assembly 110 discussedabove with respect to FIGS. 17 and 18, the embodiment of the filterassembly 110 illustrated in FIG. 19 includes filter slats 150 that aredesigned to move between an open configuration that includes gapsbetween the filter slats 150 and the illustrated closed configuration,in which the filter slats 150 contact one another to form a unifiedfilter surface 152 as a result of the overlap and engagement of thefilter slats 150. The embodiment of the filter assembly 110 illustratedin FIG. 19 includes a first and a second motor 190 and 192 that areoperably coupled to upper spools 194 and lower spools 196 andcommunicatively coupled to the control panel 82 of the HVAC unit 12. Anupper transfer belt 198 is loaded onto the upper spools 194, and a lowertransfer belt 200 is loaded onto the lower spools 196, and the transferbelts 198 and 200 pass through corresponding slots 202 in the filterslats 150. Additionally, a first set of filter slats, 150A, 150C, 150E,150G, 150I, and 150K, is coupled to the upper transfer belt 198 androtates in a first direction, as indicated by the arrow 204A, inresponse to movement of the upper transfer belt 198 to switch the filterassembly 110 to the illustrated closed configuration. A second set offilter slats, 150B, 150D, 150F, 150H, and 150I, is coupled to the lowertransfer belt 200 and rotates in response to movement of the lowertransfer belt 200, as indicated by the arrow 204B, to switch the filterassembly 110 to the illustrated closed configuration. Like the filterassembly 110 of FIG. 18, the unified filter surface 152 of theillustrated embodiment includes triangular valleys 136 that extend orprotrude in the direction of the airflow 102, giving the unified filtersurface 152 a zig-zag or accordion-like profile.

With the foregoing in mind, in certain embodiments of the filterassembly 110 that include filter slats 150, the control panel 82 mayprovide control signals to move the filter slats 150 between the openconfiguration and the closed configuration (including intermediateconfigurations) in response to one or more conditions of the HVAC unit12 and/or the outdoor environment. For example, in certain embodiments,the control panel 82 provides control signals to put the filter assembly110 in the open configuration by default or an intermediateconfiguration based on a determination of material size to be filtered,which may be based on location and/or weather. It may be appreciatedthat the open configuration of the filter assembly 110 minimizes thepressure drop across the filter assembly 110, which reduces powerconsumption of the fans 32 and the HVAC unit 12. Additionally, incertain embodiments, the open configuration may include gaps 182suitably sized (e.g., 1 mm or more) to block coarse debris fromtraversing the air intake 100. However, during operation of the HVACunit 12, when the control panel 82 determines that the current operatingtime falls with a predetermined time window when debris is known toincreases in the outdoor environment (e.g., pollen season, dust stormseason, morning, evening), then the control panel 82 may providesuitable control signals to switch the filter assembly 110 to the closedconfiguration, which blocks the coarse and fine debris from reaching theheat exchanger 28 within the HVAC unit 12. For such embodiments, thecontrol panel 82 may be programmed (e.g., during installation ormaintenance) to define the predetermined time windows when the finedebris is known to increase, and may also include a clock that tracksthe passage of time. In other embodiments, the control panel 82 may becommunicatively coupled to an external service, such as an onlineweather or air-quality service that provides information regardingoutdoor debris in the air, and the control panel 82 may determine whento switch the filter assembly 110 to the closed configuration based oninformation received from the external service.

In another example, the control panel 82 of the HVAC unit 12 providescontrol signals to place the filter assembly 110 in the closedconfiguration by default in order to block both coarse and fine debrisfrom traversing the air intake 100. Additionally, the control panel 82may receive measurements from the pressure sensor 116 and monitor thepressure drop across the filter assembly 110 over time. As coarse andfine debris accumulates within the filter slats 150 over time, thepressure drop across the filter assembly 110 increases. Once thepressure drop across the filter assembly 110 reaches a predefinedpressure threshold value, the control panel 82 may provide controlsignals to switch the filter assembly 110 to the open configuration toreduce the pressure drop across the filter assembly 110, which reducespower consumption of the fans 32 and the HVAC unit 12. Additionally, incertain embodiments, the open configuration may include gaps 182suitably sized (e.g., 1 mm or more) to block coarse debris fromtraversing the air intake 100. In certain embodiments, the filter slats150 of the filter assembly 110 are moved toward the open configurationuntil a predefined target pressure drop value is measured across thefilter assembly. Additionally, in certain embodiments, the control panel82 may activate the water spray jets 118 of the HVAC unit 12 to washdebris from the filtration material 126 of the filter slats 150 beforeswitching the filter assembly 110 to the open configuration. For suchembodiments, performing this washing step before rotating the filterslats 150 into the open configuration helps to prevent debris that haspreviously collected on the filter slats 150 from traversing the airintake 100 and reaching the heat exchanger 28. In still otherembodiments, the control panel 82 may first activate the water sprayjets 118 while the filter assembly 110 is in the closed configuration,and, once the filter assembly is dry, determine if the pressure drop hasdecreased below the pressure threshold value before resorting toswitching the filter assembly 110 into the open position. Additionally,when the control panel 82 determines that the pressure drop is stillabove the predetermined threshold after washing and/or attempting toswitch to the open configuration, the control panel 82 may provide anindication that maintenance of the HVAC unit 12 should be performed.

The technical effects of the present disclosure include providingimproved filter assemblies for filtering outdoor airflows that limit thepressure drop across the filter assembly. More specifically, presentembodiments include filter assemblies that are designed to be disposedupstream of a microchannel heat exchanger of the HVAC system to capturedebris and prevent it from depositing onto a surface of the heatexchanger. In certain embodiments, the disclosed filter assemblyincludes an inner and an outer coarse filter with a fine filterremovably loaded therebetween. For such embodiments, the fine filterincludes features, such as valleys or extensions, that protrude in thedirection of air flow and that accumulate captured debris while stillenabling suitable airflow, and limited pressure drop, across the filterassembly. In other embodiments, the filter assembly includes a set ofmovable filter sections, which can be selectively positioned and movedbetween an open configuration and a closed configuration that blocksboth coarse and fine debris. Further, by adjusting the positions of thefilter sections to provide a minimum amount of filtration that issuitable for a given environment and time, such embodiments minimize thepressure drop associated with the filter assembly, improving theefficiency and the operation of the HVAC system.

1. A filter assembly configured to filter an airflow entering an airintake of a heating, ventilation, and/or air conditioning (HVAC) unit,the filter assembly comprising: a support structure; and a plurality offilter slats, each comprising a fine filtration material, each disposedwithin the support structure, and wherein the plurality of filter slatsis configured in a louvered relationship and actuated between a closedconfiguration through which the airflow passes and an open configurationthrough which the airflow passes.
 2. The filter assembly of claim 1,wherein the open configuration comprises gaps between adjacent filterslats of the plurality of filter slats through which the airflow passes,and wherein the closed configuration comprises contact between theadjacent filter slats to form a unified filter surface through which theairflow passes.
 3. The filter assembly of claim 2, wherein the gaps ofthe open configuration are configured to capture coarse debris from theairflow, and wherein the unified filter surface of the closedconfiguration is configured to capture both the coarse debris and finedebris from the airflow with the fine filtration material.
 4. The filterassembly of claim 1, comprising a first motor operably coupled to afirst portion of the plurality of filter slats, wherein the first motoris configured to rotate the first portion of the plurality of filterslats from the open configuration to the closed configuration in a firstdirection, and to rotate the first portion of the plurality of filterslats from the closed configuration to the open configuration in asecond direction opposite the first direction.
 5. The filter assembly ofclaim 4, comprising a second motor operably coupled to a second portionof the plurality of filter slats, wherein the second motor is configuredto actuate the second portion of the plurality of filter slats from theopen configuration to the closed configuration in the second direction,and to rotate the second portion of the plurality of filter slats fromthe closed configuration to the open configuration in the firstdirection.
 6. A filter assembly configured to selectively filter debrisfrom an airflow entering an air intake of a heating, ventilation, and/orair conditioning (HVAC) unit, the filter assembly comprising: a motor; atransfer device operably coupled to the motor; and a plurality of filterslats in louvered relationship, each comprising a fine filtrationmaterial, each operably coupled to the motor via the transfer device,and configured to be selectively actuated between a closed configurationand an open configuration.
 7. The filter assembly of claim 6, whereinthe open configuration positions the plurality of filter slats to filtercoarse debris from the airflow in gaps between adjacent filter slats,and wherein the gaps are approximately 1 millimeter (mm) wide or more.8. The filter assembly of claim 6, wherein the open configurationpositions the plurality of filter slats to filter coarse debris from theairflow in gaps between adjacent filter slats, wherein the gaps arelarger than approximately 1 mm wide and allow coarse debris and finedebris to enter the air intake of the HVAC unit, and wherein there is nosubstantial pressure drop across the filter assembly in the openconfiguration.
 9. The filter assembly of claim 6, wherein the closedconfiguration positions the plurality of filter slats such that adjacentfilter slats contact one another to form a unified filter surface tofilter coarse debris and fine debris from the airflow with the finefiltration material.
 10. The filter assembly of claim 9, wherein theunified filter surface includes valleys that extend in a direction ofthe airflow and are configured to accumulate coarse and fine debris fromthe airflow.
 11. The filter assembly of claim 10, wherein the valleyscomprise triangular valleys formed where the adjacent filter slatscontact one another in the closed configuration.
 12. The filter assemblyof claim 6, wherein the plurality of filter slats comprise a first setof filter slats configured to be rotated in a first direction to yieldthe open configuration and configured to be rotated in a seconddirection to yield the closed configuration.
 13. The filter assembly ofclaim 12, wherein the plurality of filter slats comprise a second set offilter slats configured to be rotated in the second direction to yieldthe open configuration and configured to be rotated in the firstdirection to yield the closed configuration.
 14. The filter assembly ofclaim 6, comprising an additional motor and an additional transferdevice.
 15. The filter assembly of claim 14, wherein each of theplurality of filter slats is operably coupled to the additional motorvia the additional transfer device.
 16. The filter assembly of claim 14,comprising an additional plurality of filter slats, each operablycoupled to the additional motor via the additional transfer device, andconfigured to be selectively actuated between the closed configurationand the open configuration.
 17. A heating, ventilation, and/or airconditioning (HVAC) unit, comprising: a control panel configured tocontrol operation of the HVAC unit; filter assembly configured to filterdebris from an airflow entering an air intake of the HVAC unit toexchange heat with a heat exchanger of the HVAC unit, wherein the filterassembly comprises: a motor communicatively coupled to the controlpanel; a transfer device operably coupled to the motor; and a pluralityof filter slats, each comprising a fine filtration material, eachoperably coupled to the transfer device in a louvered relationship, andconfigured to be actuated between a closed configuration and an openconfiguration.
 18. The HVAC unit of claim 17, comprising at least onepressure sensor communicatively coupled to the control panel andconfigured to measure a pressure drop across the filter assembly. 19.The HVAC unit of claim 18, wherein the control panel is configured toprovide control signals to actuate the plurality of filter slats fromthe closed configuration to the open configuration in response todetermining that the measured pressure drop across the filter assemblyexceeds a predetermined pressure threshold value.
 20. The HVAC unit ofclaim 18, wherein the control panel is configured to provide controlsignals to actuate the plurality of filter slats from the closedconfiguration to the open configuration until the measured pressure dropacross the filter assembly reaches a target predetermined pressurevalue.
 21. The HVAC unit of claim 20, comprising at least one waterspray jet disposed near the filter assembly and communicatively coupledto the control panel, wherein the control panel is configured to providecontrol signals to activate the at least one water spray jet to wash atleast a portion of the debris from the plurality of filter slats beforeproviding the control signals to actuate the plurality of filter slatsto the open configuration.
 22. The HVAC unit of claim 17, wherein thecontrol panel comprises a clock and a memory configured to store atleast one predetermined time period in which the debris is expected toincrease in the airflow, wherein the control panel is configured toprovide control signals to actuate the filter slats from the openconfiguration to the closed configuration in response to determining acurrent time indicated by the clock falls within the at least onepredetermined time period.
 23. The HVAC unit of claim 17, comprising: atleast one temperature sensor communicatively coupled to the controlpanel and configured to measure a temperature of the airflow; and atleast one water spray jet disposed near the filter assembly andcommunicatively coupled to the control panel, wherein the control panelis configured to provide control signals to activate the at least onewater spray jet to cool the airflow in response to determining that themeasured temperature of the airflow is greater than a predeterminedtemperature threshold value.